Presentation
Cough and shortness of breath. Non-smoker.
Patient Data

Triangular shaped opacity medially in the right lower zone, with effacement of the right heart border silhouette.
Subtle volume loss in the right hemithorax.
Left lung clear. Heart size normal.
Case Discussion
When the right middle lobe collapses, it does so medially, with the collapsed lobe abutting the right atrium, so that the right heart border silhouette is effaced.
In a middle-aged patient, chest CT and bronchoscopy are the typical next investigations.
In a younger patient, the underlying cause is unlikely to be malignant, and therefore a more conservative management approach may be possible.